Study on removal of organic dyes by Fe3O4/amidation modified waste polystyrene composites

Design and fabrication of structurally optimized absorbents are important for wastewater treatment such as dyes removal. Herein, modifying the environmentally harmful waste polystyrene foam as an efficient recyclable adsorbent for organic dyes is important Magnetic amidated modified polystyrene (Fe 3 O 4 /PS-SD) was prepared by Friedel–Crafts reaction, N,N”-dicyclohexylcarbodiimide (DCC) dehydration condensation, and chemical co-precipitation reaction. Fe 3 O 4 /PS-SD had highly efficient removing performance for organic dyes in large volume of water sample solutions, and the equilibrium was achieved in 0.5 h. The maximum adsorption capacity for Methylene blue (MB), Safranine T (ST), and Congo red (CR) were 620.32 mg g −1 , 679.63 mg g −1 , and 1425.77 mg g −1 , respectively, at room temperature according to the Langmuir adsorption isotherm (R 2 > 0.91). The kinetic data of the three dyes followed pseudo-second-order kinetics. After ten regeneration cycles, the removal rate remained high (> 80%). Experimental results showed that Fe 3 O 4 /PS-SD was an excellent adsorbent for water treatment with high regeneration property and thermal stability.